7. Why would it be difficult to measure the rate of reaction for the rusting of iron?

For rusting, it is difficult to write an equation due to the complexity of the reaction. Thus, we can express the reaction like the following. According to the law of conservation of mass, the increased mass of nail and rust is the amount of oxygen.

Explanation:

I hope this helps:)

n has four pairs of electrons in the valence shell, electrons repel one another ,n has 7 protons in its nucleus, and since n has 7 protons, it must fill the second shell, giving it 4 pairs of electrons. the electrons form 3 bonds and 1 lone pair of electrons. each pair of electrons repels the other pairs, so they are equally far apart.

so all of the above

the answer is c. nacl